DESCRIPTION (applicant's abstract): The detection of pesticide residue in foods is a significant issue in food safety. Current analytical methods, however, involve complicated and expensive equipment that requires skilled operators and cannot be readily applied to field applications. Antibody based methods are possible alternatives to current pesticide detection methods; however, the development of antibodies against these small molecules is not a trivial task. Oligonucleotide ligands present distinct advantages over antibodies with regards to development, production, and stability. For these reasons, the development of pesticide detection methods that utilize these binding molecules is attractive. Our company is interested in utilizing oligonucleotide ligands for the development of pesticide assays that can be readily utilized in the field to analyze food samples. As a first step in the development of these tests, we propose to develop oligonucleotide ligands against the organophosphate pesticide fenitrothion, develop and optimize an enzyme assay using the ligands, then compare the assay performance with that of a commercially available immunoassay. If successful, this novel application of oligonucleotide ligands would lead to the development of commercially viable, field deployable methods for detection of pesticide residue on foods. PROPOSED COMMERCIAL APPLICATION: Rapid, field deployable methods for detection of pesticides would have direct relevance to food producers and processors as well as regulatory agencies of all nations for surveillance of these chemical compounds in foods thus giving them a global and potentially huge commercial market.